FONTANA, Calif.--The tolerances in racing engineering these days are
astonishingly tight, whether it's electrical or mechanical.

We heard this time and again as we toured the garage and pit lane
here as part of the Littelfuse Speed2Design project this fall with
James "Sulli" Sullivan of SH Racing. The engineering insight is
exceptional but abstracted somewhat as Sullivan talks about
optimizing a IndyCar vehicle for conditions and tracks. It's not so
abstracted when the subject of Dan Wheldon comes up. [Learn more about the Indy 500 at the Littelfuse Speed2Design site.]

Wheldon, the 2011 Indy 500 champion was killed in a horrific crash
at the Las Vegas IndyCar event on Oct. 16, 2011. The crash and his
death prompted the race league to take a step back and a hard look
at the rules that dictate how they manage that tension between speed
and safety.

The tension revolves around downforce--what keeps what
could otherwise be an airplane from flying off the track. At some
tracks and conditions, there's more or less a 1:1 ratio between the
vehicle's weight and the necessary downforce; in others downforce
can be three to four time the car's weight.

And like most engineering decisions, some tradeoffs can take
precedence over others. In the aftermath of Wheldon's crash, league
officials altered downforce rules to reduce the amount of "pack
racing" that bunches up cars and can cause accidents. That was
considered a factor in the Wheldon's
crash at Las Vegas.

But as we walked around with Sullivan here at the Auto Club
Speedway, E.J. Viso, one of three drivers on the KV Racing team,
which Littelfuse sponsored, threatened
to pull out because of downforce rules. That afternoon
on Twitter, he tweeted: “If more downforce is not fitted for this
race I’m not racing!”

The league was easing down-force pressure, but if you ease
downforce, cars have less stability and become hard to handle in
other ways. Viso didn't pull out and he finished25th after
completing just 65 of 250 laps.

Listen as Sullivan explains the physics behind downforce in auto
racing and how race teams alter their tactics and cars to suit
conditions. Earlier, Sullivan also talked about why race cars don't
turn, they rotate and gave us a breakdown of why
racing is so expensive. Related stories: